The present invention relates generally to a belt drive having a speed selection shift mechanism. In particular, the present invention relates to a shift collar that is moveable and engageable between a pair of drive pulleys.
To shift between speeds on conventional belt drive mechanisms, such as those used on agricultural combines, involves stopping the rotation of the belt drive, removing tension on the belt and moving the belt from one set of pulleys to another. Typically, to accomplish this, a tensioning mechanism for the pulley belt or belts must be disengaged or released. The belt or belts must then be moved from one set of pulleys to a second set of pulleys. Then, the belt tension mechanism must be re-engaged. Belt tension on such belt drive mechanisms is relatively high and thus a mechanical advantage device, such as a relatively long lever arm, is utilized to engage and disengage the tensioning mechanism. Moreover, moving the belt or belts can be difficult due to the length of the belts and/or the location of the belts within the framework of e.g., an agricultural combine.
Thus, what is sought is a belt drive shift mechanism for rotatable items on agricultural machines, such as combines and the like, which eliminates the need for engaging and disengaging the belt tensioning mechanism, and physically moving the belt or belts from one set of pulleys to another. However, conventional belt drive shift mechanisms have a number of drawbacks. For example, due to the arrangement, complexity and shape of conventional shifter mechanisms, such devices are very expensive, difficult to manufacture and easily susceptible to mechanical malfunction as a result of harvesting debris interfering with the mechanical operation of the shifter mechanism.
Thus, there is still a need for a shifter mechanism capable of shifting between a pair of pulleys that addresses the aforementioned drawbacks of conventional shifter mechanisms. Such a need is satisfied by the shift mechanism for a belt drive having a shift mechanism of the present invention.